• 한국대기환경학회지
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• 제8권4호
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• pp.262-268
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• 1992

The trend of international concerns on environmental conservation and domestic demand of ambient air quality improvement, specially on sulfur dioxide level has resulted in the establishment of mid-term strategy of environmental improvement and stepwise strengthening of emission regulations in this decade in Korea. Development of flue gas desulfurization(FGD) process is becoming an essential task to be accomplished especially for the power plants and large industrial facilities. This study is an initial stage researc focusing on the mass transfer principles in wet type FGD process and the effects of operating variables of a jet bubbling scrubber utilizing limestone slurry on sulfur dioxide removal efficiency. Experimental results showed this type of scrubbing system has some advantages in terms of mass transfer mechanism and removal efficiency. More rigorous research is needed for the reaction system and the comparison with existing FGD processess for the possible development of a process which is compatative in view of installation cost and treatment of by-products.

• 한국응용과학기술학회지
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• 제20권2호
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• pp.154-164
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• 2003

This paper has applied a simple model to the mass transfer mechanism of Cr(VI) with crownether in a batch-type, supported liquid membrane module. Concentration at pH 3 are as follows : 0.012 kmol/$m^3{\le}$18-crown-6${\le}$0.036 kmol/$m^3$ and 20 g/$m^3{\le}$ Cr(VI)${\le}$500 g/$m^3$. The measured values of forward- and backward-reaction rate constants between Cr(VI) and 18-crown-6 were used to simulate the model with the mass conservation equation and associated boundary conditions. Comparison between the experimental and simulated facilitated factor of Cr(VI) transport led to classification of reaction regions.

• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.840-848
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• 2006

We carried out numerical studies to investigate the single- and two-phase flow characteristics in the single- and multi-channels. We used the finite volume method to solve the mass and momentum conservation equations. The volume of fluid model is used to predict the two-phase flow in the channel. We obtained the distribution of velocity fields, pressure drop and air volume fraction for different water mass flow rates. We also calculated the distribution of mass flow rates in the multi-channels to understand how the flow is distributed in the channels. The calculated results for the single- and two-phase flow are partly compared with the present experimental data both qualitatively and quantitatively, showing relatively good agreement between them. The numerical scheme used in this study predicts well the characteristics of single-and two-phase flow in a multi-channel.

• Membrane and Water Treatment
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• 제11권5호
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• pp.353-361
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• 2020

The present study deals with a numerical investigation of heat and mass transfer in a Sweeping Gas Membrane Distillation (SGMD) used for desalination. The governing equations expressing the conservation of mass, momentum, energy and species with coupled boundary conditions were solved numerically. The slip boundary condition applied on the feed saline solution-hydrophobic membrane interface is taken into consideration showing its effects on profiles and process parameters.The numerical model was validated with available experimental data and was found to be in good agreement particularly when the slip condition is considered. The results of the simulations highlighted the effect of slip boundary condition on the velocity and temperature distributions as well as the process effectiveness. They showed in particular that as the slip length increases, the permeate flux of fresh water and process thermal efficiency rise.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.108-113
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• 1998

A numerical investigation for the flow, heat and mass transfer characteristics of the grooved evaporating tube with the films flowing down on both the inside and outside tube walls has been carried out. The condensation occurs along the outside wall while the evaporation takes place at the free surface of the inside film. The 3-D transport equations for momentum and energy are solved by using the FVM(Finite Volume Method). The free surface shape is tracked by the moving grid technique satisfying the SCL(Space Conservation Rule). Due to the secondary motion of the fluid, the film thins at the crest, while thickens at the valley. The velocity and temperature fields as well as the amounts of the condensed and evaporated mass have been successfully predicted for various operating conditions and groove shapes.

• 보존과학회지
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• 제34권2호
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• pp.129-135
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• 2018

Scientific investigation of cultural heritage can provide important information to understand the context of the object. To know the characteristics of the material is also an essential part of objects management and conservation. However, the identification and characterization of organic dyes used in archaeological and historical textiles are often limited by the restrictions in sampling. To cope with the difficulties, applications of high-performance techniques of surface analysis, such as Time of Flight-Secondary Ion Mass Spectra (TOF-SIMS) could be considered as a non or micro-destructive option. This study aims to examine the applicability of TOF-SIMS analysis to the detection of organic dyes from historical textiles. A group of silk fabrics dyed with vegetable dyes were artificially photo-aged to different degrees and analyzed with TOF-SIMS. Molecular and fragment ions from indigo were successfully detected from the aged samples; however, only some fragment ions were observed from gardenia and safflower dyed fabrics. Further studies with actual historical samples with extended examination scope would be necessary to assess the validity of this technique.

• 한국환경복원기술학회지
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• 제13권5호
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• pp.180-188
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• 2010

This study was carried out to evaluate the analysis of environmental change (forest resources and soil water conservation by land types) after planting for prevention of between 2003 and 2006 from the stone hazarding areas in Guizhou province, China. Mean diameter growth of the trees was highest for Melia azedarach, followed by Robinia pseudoacacia, Lonicera fulvotomentosa, Choerospondias axillaris, Cupressus duclouxiana, and Eucommia uimoides Oliv. Mean height growth of the trees was greatest for R. pseudoacacia, followed by Ilex kudincha, M. azedarach, C. duclouxiana, C. axillaris, E. uimoides Oliv, Zanthoxylum bungeanum, and L. fulvotomentosa. Tree biomass was greater at the afforestation sites by 1.22-1.71 ton/ha compared to that of severely eroded mountain areas. The capacities of soil water conservation by land types were 2,790 ton/ha at latent rock desertification farmland, 2,655 ton/ha at rock desertification farmland, 1,680 ton/ha at dolomite sandstone hilly country, 1,650 ton/ha at halfstony hilly country, and 1,590 ton/ha at karst physiognomy site. Soil erosion was estimated to be 1,285 ton/$km^2$ which had been 2,178 ton/$km^2$ before afforestation. Also, we should be continuative manage after planting for prevention of the stone hazarding areas in Guizhou province, China.

• Plant Biotechnology Reports
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• 제2권3호
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• pp.213-218
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• 2008

Swertia chirata is an endangered gentian species that prefers to grow at higher altitudes. This ethnomedicinal herb is known primarily for its bitter taste caused by the presence of important phytochemicals that are directly associated with human health benefits. Due to a continuous loss of habitat and inherent problems of seed viability and seed germination, alternative strategies for propagation and conservation are urgently required to prevent the possible extinction of this species. We have formulated a reproducible protocol for the rapid propagation and conservation of this plant using leaves taken from in vitro shoot cultures. Direct induction of more than seven shoot buds per explant was achieved for the first time when the explants were placed on MS medium supplemented with $2.22{\mu}M$ N-6-benzyladenine, $11.6{\mu}M$ kinetin, and $0.5{\mu}M$ ${\alpha}-naphthalene$ acetic acid. Direct organogenesis was noted exclusively from the adaxial surface of the basal segments of leaves. Leaves closer to the apical meristem were more responsive than those farther away from the meristem. Plants raised through direct organogenesis were evaluated for their clonal fidelity by chromosomal analysis and DNA fingerprinting. Complete plants were successfully transferred to the field condition and produced viable seeds. Given the enormous potential of this age-old medicinal plant in terms of potential health-benefitting drugs, this protocol can be used for commercial propagation purposes and to initiate future genetic improvement studies.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.732-740
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• 2021

Scattering resonance of medium mass nuclides leads complex spectrum in the fast reactor, which requires thousands of energy groups in the spectrum calculation. When the broad-group cross sections are collapsed, reaction rate cannot be completely conserved. To eliminate the error from energy collapsing, the Super-homogenization method in energy collapsing (ESPH) was employed in the fast reactor code SARAX. An ESPH factor was derived based on the ESPH-corrected SN transport equation. By applying the factor in problems with reflective boundary condition, both the effective multiplication factor and reaction rate were conserved. The fixed-source iteration was used to ensure the stability of ESPH iteration. However, in the energy collapsing process of SARAX, the vacuum boundary condition was adopted, which was necessary for fast reactors with strong heterogeneity. To further reduce the error caused by leakage, an additional conservation factor was proposed to correct the neutron current in energy collapsing. To evaluate the performance of ESPH with conservation factor, numerical benchmarks of fast reactors were calculated. The results of broad-group calculation agreed well with the direct full-core Monte-Carlo calculation, including the effective multiplication factor, radial power distribution, total control rod worth and sodium void worth.

• Journal of Plant Biotechnology
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• 제47권4호
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• pp.330-336
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• 2020

Ex-situ conservation of the ornamental and medicinal orchid, Coelogyne stricta, was performed by mass propagation using seed culture. Propagation stages were optimized using full- and half-strength solidified MS medium with different phytohormones. Maximum seed germination (88 ± 0.5% over 6 weeks of culture) was achieved on half-strength MS medium supplemented with 15% coconut water. Maximum shoot numbers were found on full-strength MS medium supplemented with 1 mg/L BAP, 2 mg/L Kinetin, and 10% coconut water, while the longest root was developed on full-strength MS medium with 1.5 mg/L IBA. A 2:1:1 combination of coco-peat, pine bark, and sphagnum moss was found to be a suitable potting mixture resulting in 80% seedling survivability. The cytotoxic activity of extracts of both wild plants and in vitro-developed protocorms was determined using an MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay on a cervical cancer cell line. The wild plant extract inhibited the growth of 41.99% of cells, showing that this extract has moderate cytotoxic activity toward cervical cancer cells.